1. Field of the Invention
This invention relates to lubricants and, more particularly to food grade lubricating oils which are especially useful as hydraulic oils, gear oils, and compressor oils for equipment in the food service industry.
2. Background
The equipment used in the food processing industry varies by segment with the three leading segments comprising meat and poultry, beverages, and dairy. While the equipment varies from segment to segment, the moving parts such as bearings, gears, and slide mechanisms are similar and often require lubrication. The lubricants most often used include hydraulic, refrigeration, and gear oils as well as all-purpose greases. These food industry oils must meet more stringent standards than other industry lubricants.
Due to the importance of ensuring and maintaining safeguards and standards of quality for food products, the food industry must comply with the rules and regulations set forth by the United States Department of Agriculture (USDA). The Food Safety and Inspection Service (FSIS) of the USDA is responsible for all programs for the inspection, grading, and standardization of meat, poultry, eggs, dairy products, fruits, and vegetables. These programs are mandatory, and the inspection of non-food compounds used in federally inspected plants is required.
The FSIS is custodian of the official list of authorized compounds for use in federally inspected plants. The official list (see page 11-1, List of Proprietary Substances and Non-Food Compounds, Miscellaneous Publication Number 1419 (1989) by the Food Safety and Inspection Service, United States Department of Agriculture) states that lubricants and other substances which are susceptible to incidental food contact are considered indirect food additives under USDA regulations. Therefore, these lubricants, classified as either H-1 or H-2, are required to be approved by the USDA before being used in food processing plants. The most stringent classification, H-1, is for lubricants approved for incidental food contact. The H-2 classification is for uses where there is no possibility of food contact and assures that no known poisons or carcinogens are used in the lubricant. The present invention pertains to a H-1 approved lubricating oil. H-1 approved oil and the term "food grade" will be used interchangeably for purpose of this application.
Several market factors accentuate the need for a superior food grade lubricating oil. Some manufacturers prefer to use only H-1 approved oils to avoid the threat of noncompliance. Reducing contamination risks and inventory carrying costs associated with stocking multiple inventories of varying viscosity/FDA approval level oils also provides an economic incentive for exclusive use of H-1 approved oils. Furthermore, other firms, reliant upon company image as a marketing resource, may elect to take the conservative approach to health and safety issues and utilize only H-1 approved oils. All of the above concerns are addressed by the exclusive use of H-1 approved oils.
In addition to meeting the requirements for safety set by federal regulatory agencies, the product must be an effective lubricant. Lubricating oils for food processing plants should lubricate machine parts, resist viscosity change, resist oxidation, protect against rusting and corrosion, provide wear protection, prevent foaming, and resist the formation of sludge in service. The product should also perform effectively at various lubrication regimes ranging from hydrodynamic thick film regimes to boundary thin film regimes.
The oxidation, thermal, and hydrolytic stability characteristics of a lubricating oil help predict how effectively an oil will maintain its lubricating properties over time and resist sludge formation. Hydrocarbon oils are partially oxidized when contacted with oxygen at elevated temperatures for prolonged periods of time. The oxidation process produces acidic bodies within the lubricating oil which are corrosive to metals often present in food processing equipment. Many metals present in food processing equipment and in contact with both the oil and the air are effective oxidation catalysts which further increases the rate of oxidation. Oxidation products contribute to the formation of sludges which can clog valves, plug filters, and result in the over-all breakdown of the viscosity characteristics of the lubricant. Under some circumstances, sludge formation can result in pluggage, complete loss of oil system flow, and failure or damage to machinery.
The thermal and hydrolytic stability characteristics of a lubricating oil reflect primarily on the stability of the lubricating oil additive package. The stability criteria monitor sludge formation, viscosity change, acidity change, and the corrosion tendencies of the oil. Hydrolytic stability assesses these characteristics in the presence of water. Inferior stability characteristics result in a lubricating oil that loses lubricating properties over time and precipitates sludge.
It is, therefore, desirable to provide an improved food grade lubricating oil which overcomes most, if not all, of the preceding problems.